This invention is directed to the use of coated nonwoven fabrics as shoe components.
Various types of materials are used for footwear components. Leather is probably the oldest and best-known material for use in footwear. Leather is known to be used for both linings and for uppers. Artificial leathers and other man-made materials are also used to make uppers, especially in low-end shoes. In fact, such footwear is typically made without a lining, but they are not as comfortable as lined shoes. As understood in the footwear field, upper is the part of a shoe or boot that is above the sole and encloses the foot of the wearer either totally or partially. It is understood that hereafter the term shoe will at times to refer to footwear, generally.
Polyurethane-coated fabrics (PUCFs) are used for making shoes and account for about one-half of the uppers used in women's shoes. They account for a lower, but significant, proportion of men's and children's shoes. Shoes made from PUCFs usually have a separate lining. PUCFs fall into two main categories Transfer PUCFs and Coagulated PUCFs. Transfer PUCFs are generally considered as conventional PUCFs because they were introduced first. The process used to make them is sometimes call the dry process. Coagulated types are made using a wet process and this is particularly true of dip-coagulation. Transfer coated fabrics usually comprise a woven fabric base of either cotton or a polyester/cotton blend, and a top skin of PU attached by means of an adhesive.
The coating is normally a polymer film of about 0.025 0.05 mm thickness and the woven fabric base is a 4×1 twill structure. The PU top skin serves two functions to make the fabric look attractive and to protect it from the rigors of wear. Coagulated PUCFs were developed in response to the need for upper materials having breathable properties yet at a competitive price. They offer a number of benefits over transfer coated PUCFs, such as, better hand, attractive appearance and non-fray characteristics.
There are two types of coagulated PUCFs; dip-coagulated and top-coagulated. The dip-coagulated method is the most widely used in Europe and North America, while the top-coagulated type is most widely used in Asia and the Pacific Rim. The main feature of a dip-coagulated PUCF is that the base fabric is completely immersed in a viscous PU solution that both penetrates and coats the weave of the base fabric.
Although PUCFs are currently more popular, the first coated fabrics on the market were the polyvinyl chloride (PVC) coated types. The structure of the material consists of woven, knitted or non-woven base fabrics coated with a layer of plasticized PVC, which can have either a solid or a cellular form.
Although woven base fabrics have typically been used for PUCFs, non-woven fabrics are being used increasingly, especially in dip-coagulated PUCFs. The advantages of non-wovens include higher levels of strength and tear resistance and more uniform properties in both the warp and weft directions, which correspond to the machine and cross machine directions, respectively, in a nonwoven fabric.